The heart with its connecting vessels is the first organ to form and function and the organ most affected by disease. During development an orchestrated network of transcriptional regulators control the coordinated spatial and temporal course of various cellular processes including specification, differentiation and morphogenesis, all absolutely essential to achieve a fully functional organ crucial from birth until death. Diseases affecting the cardiovascular system arise throughout life, as a newborn being the most common congenital birth defect worldwide, and as an adult with i.e. myocardial infarction being the number one killer worldwide. Although progress has been made in understanding what processes drives the heart, we still only begin to understand the complexity underlying the fundamental molecular mechanisms responsible for making and maintaining the heart. David Hassel has a long-standing expertise in deploying the zebrafish to decipher novel mechanisms involved in cardiovascular development and heart function. In its seminar he will give an overview of its published and unpublished contributions in cardiovascular development, heart function and cardiac regeneration.